This invention relates generally to a novel means of preventing the paper in a chain delivery section of a printing apparatus from wrinkling by substituting the apparatus of the present invention for the so-called star wheel or star wheels of the prior art. More particularly, the invention concerns an improvement in, e.g., the chain delivery section of a printing apparatus, which chain delivery section has a pair of continuous chains, upon which chains are mounted a plurality of paper griping members, wherein the chains include a plurality of pairs of links pivotally attached by pintles, comprising a pair of opposing clips detachably mountable on a link on the respective ones of the chains, without the need for adding a protrusison to the link or pintle, and including a and paper contacting members longitudinally adjustably mounted on the bar. This system allokws for speedy adjustment of both the placement of the bar along the chains and the contacting members along the bar.
In the past, it has been common to prevent wrinkling of the paper as it is transported onto, e.g., the chain delivery section, where it is gripped by the paper gripping members to be transported by the chain delivery section to a point where the paper gripping members release the paper and deposit it in a desired location, by using a so-called star wheel or star wheels which press against the paper and the cylinder which is delivering the paper to the chain delivery section at a point or points between the paper gripping members. However, should the bearing surfaces on the star wheels contact the paper at a point at which it has just freshly been printed, a series of visible marks or tracks will be left by the wheel where it has contacted the print.
It is therefore desirable to be able to adjust, with as much flexibility as possible, the points at which the star wheel, or other means of preventing the paper from wrinkling, contacts the printed sheets.
One manner of accomplishing this is shown in the patent to Stussi, U.S. Pat. No. 2,025,481, issued on Dec. 24, 1935. In the patent to Stussi there is shown a bar or axle which extends between protrusions extending from the pintles of one or more of the links in the chain drive chains. On the bar or axle are mounted a plurality of disc-shaped paper contacting members which are adjustable longitudinally along the bar or axle.
While such arrangements have exhibited at best a degree of utility in providing the necessary flexibility for adjusting the contact points on the printed sheets, room for significant improvement remains. One problem which exists with the apparatus shown in the patent to Stussi is that the chain drive must be modified to provide the protrusions from the pintles, and unless such protrusions are placed on each pintle throughout the chain in the chain drive, a degree of flexibility in locating the contact point is lost due to inability to select discrete positions for the bar or axle throughout the length of the chain drive. The second problem which exists in the apparatus shown in the patent to Stussi is that, because the axle or bar can only be located at a plurality of discrete locations, based on the spacing of the protrusions from the pintles, and because the paper contacting members are disc-shaped, rather than eccentric the contacting points can only be adjusted along a plurality of discrete lines running transverse to the paper passing through the printing apparatus, by moving the paper contacting members longitudinally along the bar or axle. This is because the location of the bar or axle is fixed to a plurality of discrete positions along the chain drive and the disc shape of the paper contacting members fixes a single point at which the disc will contact the paper for any given bar location. Another problem which exists in the patent to Stussi, besides the lack of flexibility in the location of the contacting points, is the down time created by the necessity for unscrewing the bar or axle to remove it from the protrusions and the replacement of the bar or axle on a different pair of protrusions in order to adjust for different printing patterns in successive printing runs. Other methods of fixing crosspieces allow for attachment without modification of the chain, but suffer from this same setback of excessive time required for repositioning the crosspiece.
The problems enumerated in the foregoing are not intended to be exhaustive, but rather are among many which tend to impair the effectiveness of previously known means for preventing paper wrinkling as the paper is passed onto the chain delivery section of a printing apparatus. Other noteworthy problems also exist; however, those presented above should be sufficient to demonstrate that the prior art means for preventing paper wrinkling as the paper is passed onto the chain delivery section of a printing apparatus appearing in the art have not been altogether satisfactory.